The 20 laboratories and 300 personnel that comprise the HSS Research Institute are subspecialized in research that can improve outcomes and quality of life for people with orthopedic and rheumatic conditions. This week, I discussed new and exciting ways we are looking into the prevention of arthritis after knee ligament injury in several sessions at the American Academy of Orthopaedic Surgeons 2021 annual meeting.

Four bands of connective tissue called ligaments support the knee joint: the anterior cruciate ligament (ACL), posterior cruciate ligament, medial collateral ligament and lateral collateral ligament. Ligament damage, such as a tear from a sports injury, makes the knee joint unstable. About half of patients who experience injury to the ACL develop degeneration of cartilage that can lead to knee arthritis over about 15 years. This late effect can be particularly life-altering for young athletes.

HSS research is driven by the fact that we are seeing an increasing number of patients with these problems. Surgery can fix the initial problem of a torn ACL or cartilage and stabilize an injured knee, but we are striving to develop new treatments to prevent post-traumatic arthritis that happens later.

Our researchers have unparalleled access to patient data and tissue samples, making HSS a living laboratory for translating basic research insights into cutting-edge treatments. We’re investigating ways to prevent the development of arthritis after knee ligament injury from three different angles. First, we are analyzing changes at the tissue and cellular level in basic laboratory studies and with use of state-of-the-art quantitative magnetic resonance imaging (MRI) techniques that provide unparalleled information on changes in the microscopic structure of cartilage, going far beyond the diagnostic capability of standard MRIs.

Second, we are conducting biomechanical studies using knees from human cadavers, simulating typical gait and loads on joint surfaces and seeing how injury to ligaments and cartilage damage affects movement of the joint. Simulator technology makes it possible to perform thousands of repetitive movements in a much shorter period than observing changes in patients. The biomechanical studies are being paired with 3D computer modeling, helping us to better understand and predict abnormal stresses on the cartilage that lead to arthritis. There are numerous factors that can lead to post-traumatic arthritis, and our hope is that these models will provide insights into why some patients develop arthritis while others do not.

Third, I am leading a new, multi-institutional clinical research study evaluating the use of platelet-rich plasma (PRP) injections as a potential treatment for reducing the risk of developing knee arthritis after an ACL injury. PRP injections contain platelets concentrated from the patient’s own blood. These platelets provide a rich source of anti-inflammatory chemicals and growth factors known to stimulate repair processes. We want to determine if it can combat the inflammation that is a big culprit behind progressive degeneration in the joint.

We plan to recruit patients with ACL injuries. Patients will be randomly assigned to receive one PRP injection at diagnosis and another during surgery to repair a torn ACL or to receive placebo injections instead and will be followed for two years.

Joint fluid samples will be analyzed over time to look for inflammatory markers by using state-of-the-art laboratory techniques and quantitative MRI techniques that will allow us to detect biochemical changes in cartilage tissue within a year or two, much faster than the development of changes on routine x-rays, which can take up to 15 years. We will combine this information with patients’ symptoms and measures of function, pain and strength.

PRP has great potential, but one of the biggest challenges to date is its variability. As a blood product, the components vary greatly between patients and even on different days from the same patient. To address this issue, we will analyze a small sample of each patient’s PRP in the lab to look for common characteristics that lead to a positive response in warding off the development of arthritis.

We are proud to be leading multiple avenues of research into new ways to prevent knee arthritis in patients with knee ligament injuries.

- Scott A. Rodeo, MD, sports medicine surgeon, Vice Chair of Orthopaedic Research and Co-director of the Orthopaedic Soft Tissue Research Program at HSS